- Default to a nice `[matrix]` banner
- There is room for improvement here when the Matrix Public Archive gets it's own logo (https://github.com/matrix-org/matrix-public-archive/issues/94) and maybe says "Matrix Public Archive" somewhere in the banner.
- This is good enough for now (and certainly better than downstream previews using the first image on the page).
- For rooms, it will use the room avatar
Part of https://github.com/matrix-org/matrix-public-archive/issues/202
Image is sized to 1200x630 to match conventions of `og:image`.
Crafted the banner image by modifying the header on the room directory homepage and taking a node screenshot. Page zoom @ 175%
Eric Eastwood